Implantable tendon protection systems and related kits and methods

ABSTRACT

An implantable tendon protection system includes a body adapted to be implanted within a bursa overlying a tendon of a patient to protect the tendon. The body may be fixed to the tendon with adhesive, sutures, staples, and/or anchors. A surgical kit is provided with such a tendon protection system and an insertion cannula. Methods of protecting a tendon of a patient are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/763,414, filed on Feb. 8, 2013, which is a continuation of U.S.application Ser. No. 12/684,774, filed on Jan. 8, 2010, which claims thebenefit of U.S. Provisional Application No. 61/253,800, filed on Oct.21, 2009; 61/184,198 filed on Jun. 4, 2009; 61/162,234 filed Mar. 20,2009; 61/153,592 filed on Feb. 18, 2009, and 61/143,267 filed on Jan. 8,2009, the disclosures of each incorporated herein by reference.

FIELD

The present invention relates generally to orthopedic medicine andsurgery. More particularly, the present invention relates to methods andapparatus for delivery and fixation of sheet-like implants, such as fortreating articulating joints.

BACKGROUND

Injuries to soft tissue, including, for example, musculoskeletal tissue,may require repair by surgical intervention, depending upon factors suchas the severity and type of injury. Such surgical repairs can beeffected by using a number of conventional surgical procedures, forexample, by suturing the damaged tissue, and/or by mounting an implantto the damaged tissue. It is known that an implant may providestructural support to the damaged tissue, and it may also serve as asubstrate upon which cells can grow, thus facilitating more rapidhealing.

One example of a fairly common soft tissue injury is damage to therotator cuff or rotator cuff tendons. The rotator cuff facilitatescircular motion of the humerus relative to the scapula. Damage to therotator cuff is a potentially serious medical condition that may occurduring hyperextension, from an acute traumatic tear or from overuse ofthe joint. The most common injury associated with the rotator cuffregion is a strain or tear involving the supraspinatus tendon. A tear atthe insertion site of the tendon with the humerus, may result in thedetachment of the tendon from the bone. This detachment may be partialor full, depending upon the severity of the injury. Additionally, thestrain or tear can occur within the tendon itself. Treatment for astrained tendon usually involves physical cessation from use of thetendon, i.e., rest. However, depending upon the severity of the injury,a torn tendon might require surgical intervention as in the case of afull tear or detachment of the supraspinatus tendon from the humerus.Such surgical interventions include debridement, acromioplasty, andvarious procedures for reconnecting tendons to bone or strengtheningdamaged tendon to bone connections. Damage to the rotator cuff may alsoinclude degeneration. This is a common situation that arises in elderlypatients. In degenerative cases there is loss of the superior portion ofthe rotator cuff with complete loss of the supraspinatus tendon. Similarsoft tissue pathologies include tears in the Achilles' tendon, theanterior cruciate ligament and other tendons or ligaments of the knee,wrist, hand, and hip, spine, etc.

Some studies suggest that 85% of people over the age of 65 have somedegree of shoulder tendon damage. Well-established procedures exist forrepairing fully torn tendons, such as rotator cuff tendons, aspreviously mentioned. However, adequate treatments do not currentlyexist for partially torn tendons. There is a large need for lessinvasive surgical techniques and systems for effecting tendon repair,particularly for the supraspinatus tendon.

SUMMARY OF THE DISCLOSURE

In accordance with aspects of the disclosure, an implantable tendonprotection system is provided which comprises a body adapted to beimplanted within a bursa overlying a tendon of a patient. The bodycomprising a tendon engaging surface configured to attach to the tendon.The body may further comprise a sliding surface adapted to slide withrespect to the bursa. In some embodiments, the tendon engaging surfacecomprises adhesive. The body may be configured to be movable between acollapsed state in which the body may be received within a cannulacavity, and a deployed state in which the body may extend across aninterior portion of the bursa. In some embodiments, the body isconfigured to attach to a partially torn tendon. The body may comprise amiddle portion that is less flexible than an edge portion.

In some of the above embodiments, the body is constructed fromindividual layers. A first layer may comprise a sliding surface and asecond layer may comprise a tendon engaging surface, a mesh material, aplurality of fibers, and/or a bioabsorbable material. One or moreintermediate layers may be located at least partially between the firstand second layers. In some embodiments, a cushioning layer is interposedbetween the first and second layers. An intermediate layer may compriseat least one channel which may fluidly communicate with the tendonengaging surface. In some embodiments the sliding surface has a lowercoefficient of friction than that of the tendon engaging surface.

In accordance with other aspects of the disclosure, a surgical kit isprovided which comprises a system such as described above and aninsertion cannula. The insertion cannula may include a portionconfigured to enter a body of a patient. This portion includes a cavityfor receiving the system when in a collapsed state. The insertioncannula may further comprise a mechanism configured to remove the systemfrom the cavity when the insertion cannula portion is within the body ofthe patient. The removal mechanism may comprise a push rod at leastpartially located within the insertion cannula and movable along alongitudinal axis of the insertion cannula.

In accordance with other aspects of the disclosure, methods ofprotecting a tendon of a patient are disclosed. In some embodiments, themethod includes the steps of inserting a device into an at leastpartially viable bursa of the patient to a position overlying thetendon, and engaging a first surface of the implant with the tendon. Themethod may further include the step of attaching the device to thetendon. In some embodiments, the attaching step comprises the use of anadhesive. The adhesive may be urged through a channel in the device whenthe device is positioned within the body of the patient. In someembodiments, the inserting step comprises at least partially receivingthe device within a portion of an insertion instrument, inserting theportion of the insertion instrument into the body of the patient, andremoving the device from the insertion instrument while the portion iswithin the body. The device may be caused to assume the deployed stateat least partially by introducing a fluid into an inflatable portion ofthe device.

In some embodiments, the above methods may further comprise the step ofdelivering a therapeutic or diagnostic agent to tissue adjacent thedevice. The therapeutic or diagnostic agent may include a drug,anti-inflammatory agent, painkiller, antibiotic, protein, and/or ahormone.

In some embodiments, a second surface of the device is deployed to sliderelative to the bursa. The device may serve to protect a damaged portionof the tendons. In some embodiments, the device does not substantiallyreinforce the engaged tendons by transmitting a significant load of thetendons. The device may serve to remove a stimulus from nerves in theengaged tendons. The removed stimulus may include one or more ofpressure, temperature, chemical, electrical and inflammation stimulus.In some embodiments the device is not sutured to the tendons or othertissue. The inserting step may comprise the use of an arthroscopicinstrument. In some embodiments the tendon comprises a partially torntendon. The attaching step may comprise securing the device to thetendon using a plurality of anchors.

In accordance with other aspects of the disclosure, a method is providedwhich comprises identifying a partially torn portion of a tendon andcovering the partially torn portion of the tendon. In some embodiments adevice may be positioned over the partially torn portion of the tendonand fixed to the tendon. The device may be fixed to the tendon withadhesive, sutures, staples, and/or anchors. Covering the partially tornportion of the tendon may spread impinging forces across a surface areaof the device. In some embodiments a therapeutic agent that promotesgrowth of tissue into pores defined by the device may be delivered. Thetherapeutic agent may promote encapsulation of the device within acellular encapsulation layer. The therapeutic agent may induce thegrowth of synovial cells on an outer surface of the device. Thetherapeutic agent may induce the growth of bursa cells on an outersurface of the device. The therapeutic agent may desensitize stimulatednerve receptors proximate the partially torn portion of the tendon. Thetherapeutic agent may promote the growth of a cellular encapsulationbarrier over the partially torn portion of the tendon.

In some embodiments, covering the partially torn portion of the tendoninhibits the partially torn portion of the tendon from becoming a tearextending through a total thickness of the tendon. Covering thepartially torn portion of the tendon may inhibit physical stimulus ofthe partially torn portion by adjacent tissues. Covering the partiallytorn portion of the tendon may protect damaged tendon fibers frommechanical agitation by adjoining tissues. Covering the partially tornportion of the tendon may alleviate pain, which in turn may restoreshoulder function. In some embodiments, covering the partially tornportion of the tendon protects the partially torn portion of the tendon.Covering the partially torn portion of the tendon may prevent abrasionof the partially torn portion of the tendon. Covering the partially tornportion of the tendon may reduce friction between the partially tornportion of the tendon and adjacent tissues. Covering the partially tornportion of the tendon may cushion forces applied to the partially tornportion of the tendon by adjacent tissues.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an anterior view showing the upper torso of a patient with theleft shoulder shown in cross-section.

FIG. 2 is an enlarged, cross-sectional view showing the left shoulderdepicted in FIG. 1.

FIG. 3 is an enlarged, cross-sectional view showing an exemplaryimplantable device in accordance with aspects of the invention insertedinto the shoulder.

FIG. 4 is an enlarged, oblique, cross-sectional view showing anexemplary cannula inserted into the bursa of the shoulder.

FIG. 5 is an enlarged, oblique, cross-sectional view showing anexemplary delivery system inserted into the shoulder.

FIG. 6 shows the delivery system of FIG. 5 with the sheath retracted.

FIG. 7 shows the delivery system of FIG. 5 with the implantable devicecompletely deployed.

FIG. 8 shows the implantable device in place with the delivery system ofFIG. 5 removed.

FIG. 9 is an exploded isometric view illustrating an exemplaryimplantable device.

FIG. 10 is a stylized block diagram illustrating an exemplaryimplantable device coupled to a syringe.

FIGS. 11A, 11B, and 11C are a series of isometric views illustrating thedeployment of an exemplary implantable device.

FIG. 12 is a plan view illustrating an exemplary implantable device.

FIG. 13 is a side cross-sectional view taken along line A-A in FIG. 12.

FIG. 14 is a side cross-sectional view taken along line A-A in FIG. 12and illustrating the device of FIG. 12 anchored to a tendon.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

FIG. 1 is a stylized anterior view of a patient 28. For purposes ofillustration, a shoulder 26 of patient 28 is shown in cross-section inFIG. 1. Shoulder 26 includes a humerus 24 and a scapula 23. The movementof humerus 24 relative to scapula 23 is controlled by a number ofmuscles including: the deltoid, the supraspinatus, the infraspinatus,the subscapularis, and the teres minor. For purposes of illustration,only the supraspinatus 30 is shown in FIG. 1. With reference to FIG. 1,it will be appreciated that a distal tendon 22 of the supraspinatus 30meets humerus 24 at an insertion point 32.

FIG. 2 is an enlarged cross sectional view of shoulder 26 shown in theprevious figure. In FIG. 2, a head 36 of humerus 24 is shown mating witha glenoid fossa of scapula 23 at a glenohumeral joint 38. The glenoidfossa comprises a shallow depression in scapula 23. A supraspinatus 30and a deltoid 34 are also shown in FIG. 2. These muscles (along withothers) control the movement of humerus 24 relative to scapula 23.

A distal tendon 22 of supraspinatus 30 meets humerus 24 at an insertionpoint 32. In the embodiment of FIG. 2, tendon 22 includes a damagedportion 140 located near insertion point 32. Damaged portion 140includes a tear 142 extending partially through tendon 22. Tear 142 maybe referred to as a partial thickness tear. Tendon 22 of FIG. 2 hasbecome frayed. A number of loose tendon fibers 144 are visible in FIG.2.

Scapula 23 includes an acromium 21. In FIG. 2, a subacromial bursa 20 isshown extending between acromium 21 of scapula 23 and head 36 of humerus24. In FIG. 2, subacromial bursa 20 is shown overlaying supraspinatus30. Subacromial bursa 20 is one of more than 150 bursae found the humanbody. Each bursa comprises a fluid filled sac. The presence of thesebursae in the body reduces friction between bodily tissues. Injuryand/or infection of the bursa can cause it to become inflamed. Thiscondition is sometimes referred to as bursitis.

FIG. 3 is an additional cross sectional view of shoulder 26 shown in theprevious figure. In the embodiment of FIG. 3, a device 4 has beenimplanted inside subacromial bursa 20. Device 4 comprises a body 150.Body 150 is adapted to be implanted within a bursa overlying a tendon ofa patient.

In FIG. 3, body 150 of device 4 is shown overlaying tear 142. In theexemplary embodiment of FIG. 3, body 150 comprises a first side 152 anda second side 154. First side 152 comprises a sliding surface 156 andsecond side 154 comprises a tendon engaging surface 158. Sliding surface156 is adapted to slide with respect to adjacent tissues (e.g., bursatissue). Tendon engaging surface 158 is configured to attach to atendon.

In the exemplary embodiment of FIG. 3, fibers 144 of tendon 22 are fixedto device 4 by an adhesive 160. Adhesive 160 is illustrated using dotsin FIG. 3. With reference to FIG. 3, it will be appreciated thatadhesive 160 permeates a portion of device 4. Some exemplary methods inaccordance with the present detailed description include injecting anadhesive into channels defined by a device so that the adhesive exits aplurality of apertures defined by a tissue engaging layer of the device.The adhesive may elute over a large area to affix the device to atendon. Some additional exemplary methods in accordance with the presentdetailed description include injecting a therapeutic agent (e.g., adrug) into channels defined by a device so that the therapeutic agentexits a plurality of apertures defined by a tissue engaging layer of thedevice.

FIG. 4 is an isometric view of a shoulder 26. Shoulder 26 includes ahumerus 24 and a scapula 23. Humerus 24 comprises a head 36 having agenerally spherical surface. Head 36 of humerus 24 mates with a shallowdepression defined by the scapula 23 at a glenohumeral joint 38. In FIG.4, a distal tendon 22 of a supraspinatus 30 is shown meeting humerus 24at an insertion point. Supraspinatus 30 (along with a number of othermuscles) controls the movement of humerus 24 relative to scapula 23.

In FIG. 4, a subacromial bursa 20 is shown overlaying a portion ofsupraspinatus 30. Subacromial bursa 20 comprises a fluid filled sac thatacts to reduce friction between tissues in the body. In FIG. 4,subacromial bursa 20 is shown extending between a portion ofsupraspinatus 30 and an acromium 21 of scapula 23. In the embodiment ofFIG. 4, the distal end of a cannula 162 has been inserted into theinterior of bursa 20. Cannula 162 may be inserted, for example, near asite where tendon damage exists. Cannula 162 includes a shaft 164defining a lumen and a hub 166 that is fixed to a proximal end of shaft164. In the embodiment of FIG. 4, the lumen defined by cannula 162fluidly communicates with an interior of subacromial bursa 20.Accordingly, a device may be placed in the interior of subacromial bursa20 by advancing that device through the lumen defined by cannula 162.

FIG. 5 is an additional isometric view of shoulder 26 shown in theprevious figure. A delivery system 170 is shown in FIG. 5. Deliverysystem 170 of FIG. 5 comprises a sheath 3, a barrel 2, and a plunger 1.In the embodiment of FIG. 5, a device 4 is disposed inside sheath 3.Some methods in accordance with the present detailed description mayinclude the step of causing the body of a device to assume a collapsedshape and inserting the body of the device into a sheath. The sheath andthe body of the device may both be inserted into a bursa. Once insidethe bursa, the body may assume a deployed shape.

It is to be appreciated that the length of delivery system 170 may varyfrom that shown in FIG. 5 without deviating from the spirit and scope ofthe present detailed description. In useful some embodiments, a portionof delivery system 170 may extend through a cannula (e.g., the cannulashown in the previous figure). The cannula may guide the distal end ofdelivery system 170 to a target site.

FIG. 6 is an additional isometric view showing delivery system 170 shownin the previous figure. In the embodiment of FIG. 6, sheath 3 ofdelivery system 170 has been retracted from device 4, exposing device 4.In other embodiments, sheath 3 may remain stationary while device 4 isextended from within the sheath, or device 4 may be deployed with acombination of movements of the sheath and the device. In some usefulembodiments, device 4 assumes a generally cylindrical shape whiledisposed inside sheath 3. In the embodiment of FIG. 6, deployment ofdevice 4 has been initiated. Accordingly, device 4 is shown assuming asomewhat enlarged shape in FIG. 6.

FIG. 7 is an additional isometric view showing delivery system 170 shownin the previous figure. In FIG. 7, device 4 is shown assuming acompletely deployed shape. In the exemplary embodiment of FIG. 7, device4 is generally plate-shaped and circular when fully deployed. In someadvantageous embodiments, the body of device 4 is flexible.

Some exemplary methods in accordance with the present detaileddescription include injecting an adhesive into channels defined by adevice so that the adhesive exits a plurality of apertures defined by atissue engaging layer of the device. The adhesive may elute over a largearea to affix the device to a tendon. Delivery system 170 may bewithdrawn from shoulder 26 after the delivery of device 4 is complete.

FIG. 8 is an additional cross sectional view of shoulder 26 shown in theprevious figure. In the embodiment of FIG. 8, device 4 has beenimplanted inside subacromial bursa 20. In FIG. 8, device 4 is shownoverlaying a portion of distal tendon 22 of supraspinatus 30. In theexemplary embodiment of FIG. 8, device 4 comprises a body 150 having afirst side 152 and a second side 154. First side 152 comprises a slidingsurface 156 and second side 154 comprises a tendon engaging surface 158.In the embodiment of FIG. 8, body 150 has been positioned so that tendonengaging surface 158 engages tendon 22. Tendon engaging surface 158 maybe fixed to distal tendon 22, for example, with an adhesive. When device4 is overlaying tendon 22 as shown in FIG. 8, device 4 provides asliding surface 156 facing away from tendon 22.

FIG. 9 is an exploded isometric view illustrating an exemplary device304 in accordance with the present detailed description. In theexemplary embodiment of FIG. 9, device 304 comprises a body 350including a first layer 372, a second layer 374, a first intermediatelayer 376, and a second intermediate layer 378.

When device 304 is overlaying tendon 22, first layer 372 of device 304provides a sliding surface 356 facing away from the tendon. In theexemplary embodiment of FIG. 9, second layer 374 comprises abiocompatible material for use against the tendon surface. In theembodiment of FIG. 9, second layer 374 defines a plurality of apertures380. In one exemplary embodiment, second layer 374 comprises a meshmaterial. In some embodiments, second layer 374 may comprise a pluralityof fibers. The fibers may be interlinked with one another. When this isthe case, second layer 374 may comprise a plurality of aperturescomprising the interstitial spaces between fibers. Various processes maybe used to interlink the fibers with one another. Examples of processesthat may be suitable in some applications including weaving, knitting,and braiding.

In some useful embodiments, second layer 374 comprises one or morebioabsorbable materials. Examples of bioabsorbable materials that may besuitable in some applications include those in the following list, whichis not exhaustive: polylactide, poly-L-lactide (PLLA), poly-D-lactide(PDLA), polyglycolide (PGA), polydioxanone, polycaprolactone,polygluconate, polylactic acid-polyethylene oxide copolymers, modifiedcellulose, collagen, poly(hydroxybutyrate), polyanhydride,polyphosphoester; poly(amino acids), poly(alpha-hydroxy acid) or relatedcopolymers materials.

In the exemplary embodiment of FIG. 9, second intermediate layer 378comprises a plate defining a plurality of channels. Channels 382 ofsecond intermediate layer 378 and apertures 380 of second layer 374 mayallow a fluid to elute over a large area to device 304 to a tendon.Second intermediate layer 378 may also distribute stresses across device304. When pressure from adjacent tissues is applied to device 304, thedevice will spread that pressure across an area of a tendon covered bydevice 304. This function helps device 304 to reduce stimulus to nervesin the covered tendon.

A second inlet 386 is visible in FIG. 9. An interior of second inlet 386is in fluid communication with channels 382 of second intermediate layer378. When device 304 is in an assembled state, channels 382 fluidlycommunicate with apertures 380 defined by second layer 374. Fluid may beinjecting into channels 382 and through apertures 380 by injecting thefluid into second inlet 386. In one method in accordance with thepresent detailed description, an adhesive fluid is injected intochannels 382. The adhesive fluid may elute over a tissue engaging areaof device 304 to affix device 304 to a tendon.

In the exemplary embodiment of FIG. 9, first intermediate layer 376comprises a plurality of sheets defining a cavity 388. Various fluidsmay be injected into cavity 388. Some exemplary methods in accordancewith the present detailed description may include changing the shape ofshape of device 304. The shape of device 304 may be changed, forexample, by injecting fluid into cavity 388. A first inlet 384 is shownin FIG. 9. An interior of first inlet 384 is in fluid communication withcavity 388 of first intermediate layer 376. Fluid may be injected intocavity 388 by injecting the fluid into first inlet 384.

FIG. 10 is a stylized block diagram illustrating an exemplary device 504in accordance with the present detailed description. In the exemplaryembodiment of FIG. 10, device 504 comprises a body 550 including a firstlayer 572, a second layer 574, a first intermediate layer 576, and asecond intermediate layer 578.

In the embodiment of FIG. 10, second intermediate layer 578 comprises aplurality of flow channels. A tube 590 defines a lumen that is in fluidcommunication with the flow channels of intermediate layer. In theembodiment of FIG. 10, a proximal end of tube 590 is coupled to asyringe 592. Syringe 592 comprising a barrel 2 and a plunger 5. A fluid594 is disposed in barrel 2. Plunger 5 of syringe 592 is capable ofurging fluid 594 out of barrel 2, through tube 590, through secondintermediate layer 578, and through second layer 574. The flow of fluid594 through second intermediate layer 578 and second layer 574 isillustrated using a plurality of arrows in FIG. 10. Fluid 594 may beurged through a plurality of apertures defined by second layer 574.Fluid 594 that has exited second layer 574 is represented by a number offluid drops in the stylized block diagram of FIG. 10.

Some exemplary methods in accordance with the present detaileddescription may include the step of delivering a therapeutic ordiagnostic agent to tissue adjacent a device such as, for example,device 504 of FIG. 10. The fluid may comprise various therapeutic ordiagnostic agents. Examples of therapeutic or diagnostic agents that maybe suitable in some applications include drugs, anti-inflammatoryagents, painkillers, antibiotics, proteins, and hormones.

FIGS. 11A, 11B, and 11C are a series of isometric views illustrating thedeployment of a device 4. Some methods in accordance with the presentdetailed description may include the step of causing the body of adevice to assume a collapsed shape and inserting the body of the deviceinto a sheath. The sheath and the body of the device may both beinserted into a bursa. Once the body is inside the bursa, the body maybe urged to assume a deployed shape and/or self-deploy.

In the embodiment of FIG. 11A, device 4 is disposed inside a sheath 3 ofa delivery system 170. The body of device 4 may be wrapped at leastpartially around itself to assume a generally collapsed shape. In someuseful embodiments, the body of device 4 is capable of assuming agenerally cylindrical collapsed shape while disposed inside a lumen ofsheath 3. The body of device 4 may also be folded to assume a generallycollapsed shape.

In the embodiment of FIG. 11B, sheath 3 has been retracted from device4. Device 4 can be seen disposed outside of sheath 3 in FIG. 11B. In theembodiment of FIG. 11B, deployment of device 4 has been initiated.Accordingly, device 4 is shown assuming a somewhat enlarged shape inFIG. 11B.

In the embodiment of FIG. 11C, device 4 has been fully deployed. In theexemplary embodiment of FIG. 11, device 4 is generally plate shaped whenfully deployed. In FIG. 4, the outer edge of device 4 is shown having agenerally circular shape. In the exemplary embodiment of FIG. 11, device4 comprises a body 150 having a first side 152 and a second side 154.First side 152 comprises a sliding surface 156 and second side 154comprises a tendon engaging surface 158. In some useful methods, device4 is oriented over a tendon so that tendon engaging surface 158 engagesthe tendon.

FIGS. 12 through 14 show an additional device 700 in accordance with thepresent detailed description. Device 700 may be used, for example, tocover an injured portion of a tendon. FIG. 12 is a top view of device700. FIG. 13 is section view of device 700 taken along section line A-Ashown in FIG. 12. FIG. 14 is a section view similar to FIG. 13 showingdevice 700 in place over tendon 736.

As best seen in FIG. 13, exemplary device 700 comprises a base 702having a first major side 704 and a second major side 706 that isopposite first major side 704. In this embodiment, first major side 704comprises a generally concave surface 720 and second major side 706comprises a generally convex surface 722. A sheet 724 of device 700 maybe provided to overlay first major side 704 of base 702 and generallyconforms to the shape of concave surface 720.

As shown in FIG. 13, sheet 724 of device 700 defines a cavity 726. Insome useful embodiments, cavity 726 is dimensioned to receive a portionof a suprapinatus tendon overlying the head of a humerus. In theexemplary embodiment of FIG. 13, cavity 726 has a generallyhemispherical shape. It will be appreciated that the radius of cavity726 may vary across cavity 726 without deviating from the spirit andscope of the present description. With reference to the figures, it willbe appreciated that a skirt portion 728 of sheet 724 extends beyond base702 in this embodiment.

In some useful embodiments, sheet 724 comprises a material defining aplurality of pores that encourage tissue growth therein. A coating thatencourages tissue growth or ingrowth may be applied to the surfaces ofsheet 724. It will be appreciated that sheet 724 may comprise variouspore defining structures without deviating from the spirit and scope ofthe present description. In some embodiments, the sheet 724 has a poresize in the range of 150 to 200 microns. The porosity may be about 50percent. Examples of pore defining structures that may be suitable insome applications include open cell foam structures, mesh structures,and structures comprising a plurality of fibers. In some embodiments,the fibers may be interlinked with one another. Various processes may beused to interlink the fibers with one another. Examples of processesthat may be suitable in some applications include weaving, knitting, andbraiding.

Device 700 includes a plurality of anchors 730. In the exemplaryembodiment shown, each anchor comprises a coil 732. It will beappreciated that anchors 730 may comprise other elements withoutdeviating from the spirit and scope of the present description. Examplesof anchoring elements that may be suitable in some applications include:coils, barbs, hooks, stables, suture pads, and sutures. In theembodiment of FIG. 13, each anchor is disposed in a lumen 734 defined bybase 702. Some methods in accordance with the present description mayinclude the step of rotating anchors 730 to screw the anchors intotissue (e.g., tendon tissue) for fixing device 700 to that tissue. Aflexible catheter or other suitable driver may used to rotate anchors730. For example, a catheter (not shown) may be removably inserted intoeach of the lumens 734 in turn, accessing each lumen through a centralrecess 735 located in second major side 706 of base 702. In someembodiments, anchors 730 threadably engage with interior surfaces oflumens 734 to facilitate advancement of the anchor into tissue.

In FIG. 14, device 700 is shown overlaying a tendon 736. To place device700 over tendon 736, device 700 may be configured to be collapsible sothat it may be inserted into the body arthroscopically, similar to thepreviously described devices. For example, device 700 may be collapsedlike an umbrella, with its lumens 734 being substantially parallel andthe material between lumens 734 forming inwardly folding pleats when inthe collapsed state.

In the embodiment of FIG. 14, each coil 732 is shown extending out of alumen 734 and into tendon 736. Tendon 736 may be, for example, asupraspinatus tendon. With reference to FIG. 14, it will be appreciatedthat the diameter of each coil 732 has become enlarged as it exits alumen 734. In some useful embodiments, each coil 732 is biased to assumean increased diameter as it exits a lumen 734. In FIG. 14, each coil 732is shown extending through a skirt portion 728 of sheet 724 that extendsbeyond base 702, and then into tendon 736 to secure or assist insecuring device 700 to the tendon. In this embodiment, the middle andedge portions are configured to help distract a humeral head inabduction.

In other embodiments (not shown), a device may be provided with lumenshaving a steeper or shallower angle relative to tendon 736. While theexemplary device 700 shown in FIGS. 12-14 employs six anchors, otherdevices constructed in accordance with aspects of the presentdescription may be provided with a smaller or larger number of anchors.In other embodiments, sutures, staples, adhesive and/or other fastenersmay be used in conjunction with or instead of anchors 730 to securedevice 700 to the underlying tissue. Preformed holes may also beprovided in sheet 724 to allow anchors 730 to pass through. In otherembodiments, sheet 724 may be omitted. In still other embodiments, thedevice may have more or less of a cup shape, be generally flat, orinverted such that the anchors emerge from the convex side rather thanthe concave side. The device may be oblong, curved in only onedimension, or be saddle-shaped, depending on the particular anatomy itis designed to protect.

An implantable device such as previously described may be placed over apartial tear in a tendon. In some embodiments, the device may beimplanted over a tendon having micro-tear(s), abrasions and/orinflammation. Left untreated, minor or partial tendon tears may progressinto larger or full tears. According to aspects of the presentinvention, a small or partial tear may be treated by protecting it withan implantable device as described above. Such early treatment canpromote healing and prevent more extensive damage from occurring to thetendon, thereby averting the need for a more involved surgicalprocedure.

The implanted device may serve to protect a tendon from a stimulus. Thestimulus may comprise one or more of the following: pressure, friction,temperature, electrical or chemical stimulus. In some embodiments, thedevice does not supplant or share any substantial load borne by atendon, but serves to protect the tendon to facilitate healing.

In some embodiments, a bursa overlying a tendon is left substantiallyintact as the device is implanted over the tendon. This may beaccomplished by creating a small incision or puncture through one wallof the bursa through which the device delivery cannula may be placed.The bursa may be filled with saline or similar fluid during theprocedure to keep it inflated, thereby providing sufficient operatingspace for deploying and attaching the implantable device. After thedevice is implanted and the delivery cannula is removed, the opening inthe bursa may be closed, such as with one or more sutures.Alternatively, it is believed that the bursa may form closure tissue byitself post-operatively. Such bursa growth may be stimulated by movementof the tendon and/or bursa relative to surrounding tissue.

In other embodiments, a portion or all of the bursa may be removedduring the implantation procedure. In these embodiments, the implantabledevice may be sized and positioned to facilitate the bursa reformingnaturally in its original location after the procedure.

As previously indicated, the implantable device may comprise anabsorbable material. In some embodiments, the purpose of the device isto protect an injured portion of a tendon during healing, provide ascaffolding for new tissue growth, and/or temporarily share some of thetendon loads. The device may induce additional tendon tissue formation,thereby adding strength and reducing pain, micro strains andinflammation. When the device is applied to a structurally intact,partially torn tendon, the initial loading of the device may be carriedby native tendon tissue until collagen is formed during the healingprocess. In some embodiments, organized collagen fibers are created thatremodel to neo tendon with cell vitality and vascularity. Initialstiffness of the device may be less than that of the native tendon so asto not overload the fixation while tendon tissue is being generated.

The implantable device may be configured to allow loading and retentionof biologic growth factors. The device and/or the growth factors may beconfigured to controllably release the growth factors. The device may beconfigured to allow transmission of body fluid to remove any degradationbi-products in conjunction with a potential elution profile ofbiologics. The device should degrade over time with minimal inflammatoryresponse. For example, particulate matter that may result fromdegradation should not generate synovitus in the joint.

In one exemplary embodiment, the implantable device has a diameter ofabout 22 mm, and has directionally specific mechanical properties. Inanother embodiment, the device is generally rectangular with a width ofabout 20 mm, a length of about 40 mm, and a thickness of about 1 mm. Inanother embodiment, the device has a length of about 30 mm. These lattertwo arrangements provide a 20 mm2 cross-sectional area transverse to theload direction.

It is desirable in some situations to generate as much tissue aspossible within anatomical constraints. In some cases where a tendon isdegenerated or partially torn, tendon loads are relatively low duringearly weeks of rehabilitation. For example, the load may be about 100 N.The strain in the tendon due to the load during rehabilitation can beabout 2%. In some of these cases, the implantable device can be designedto have an ultimate tensile strength of at least about 5 MPa. Thetensile modulus can be designed to be no more than about 50 MPa and noless than about 20 MPa. The compressive modulus can be designed to be atleast about 0.5 MPa. With a tensile modulus of 50 MPa, in order for thescaffold to strain 2% in conjunction with the degenerated tendon, thestress on the scaffold will be about 1.0 MPa. With an ultimate tensilestrength of 5 MPa, the strength of the scaffolding of the implantabledevice when first implanted will be about five times the expected loads.With a cross-sectional area of 20 mm2, the load on the scaffold will be20 N. Thus, from a load sharing perspective, the scaffold will carryabout 20% of the load to experience 2% strain.

A published value for the compressive modulus of the supraspinatustendon is in the range of 0.02-0.09 MPa (J Biomech Eng 2001, 123:47-51).The scaffold provided by the implantable device should have a highercompressive modulus than the tendon to prevent collapse of pores in thescaffold. A compressive modulus of 0.5 MPa would be about five timesgreater than the tendon.

The tissue within the device scaffold will typically be developing andorganizing during the first one to three months after implantation, soload sharing with the scaffold is desired in some embodiments. Afterthree months the tissue will typically be remodeling, so the mechanicalproperties of the scaffold should gradually decline to zero to enablethe new tissue to be subjected to load without the scaffold bearing anyof the load. If the scaffold loses modulus faster than it losesstrength, then the relative loads on the scaffold will be less at threemonths than when first implanted. For example, if the modulus of thescaffold drops 50% to 25 MPa at three months, then 2% strain of thescaffold would require a stress of only about 0.5 MPa. At the same time,if the strength of the scaffold drops about 30% to 3.5 MPa, then thestrength of the scaffold will be about seven times the anticipated loadsat three months, compared to about five times when first implanted.Therefore, with the design criteria provided above, tensile failure ofthe scaffold during the first three months should be unlikely.Accordingly, the following specifications for degradation rate arerecommended in some embodiments: an ultimate tensile strength of atleast 70% strength retention at three months; tensile and compressivemodulus of at least 50% strength retention at three months; and nominimum specification for strength and modulus at 6 months. The devicemay be designed to have a degradation profile such that it is at least85% degraded in less than 1 to 2 years after implantation.

Cyclic creep is another design constraint to be considered in someembodiments. A strain of about 2% with a 40 mm long scaffold will resultin an elongation of about only 0.8 mm. Therefore, very little cycliccreep can be tolerated in these embodiments to ensure that the scaffoldwill undergo strain with each load cycle. A test where a proposedscaffold design is cyclically strained to 2% at 0.5 Hz for 1 dayprovides 43,200 cycles, which likely exceeds the number of cyclesexperienced in three months of rehabilitation of a patient's joint.Incorporation of relaxation times should be considered in such testing.In some embodiments, a maximum of about 0.5% creep is an acceptablespecification.

Material(s) used in the implanted device should be able to withstand thecompression and shear loads consistent with accepted post surgicalshoulder motions. The perimeter of the device may have differentmechanical properties than the interior of the device, such as forfacilitating better retention of sutures, staples or other fasteningmechanisms. The material(s) may be chosen to be compatible with visual,radiographic, magnetic, ultrasonic, or other common imaging techniques.The material(s) may be capable of absorbing and retaining growth factorswith the possibility of hydrophilic coatings to promote retention ofadditives.

While the systems, kits and methods disclosed above have been discussedrelative to protecting tendons in shoulder joints, they may also beutilized to protect tendons in other articulating joints such as theknee, elbow and ankle.

While exemplary embodiments of the present invention have been shown anddescribed, modifications may be made, and it is therefore intended inthe appended claims to cover all such changes and modifications whichfall within the true spirit and scope of the invention.

What is claimed is:
 1. A method of implanting an implant in a shoulderregion of a patient comprising: inserting a distal end of an implantdelivery device into a shoulder region of the patient proximate asupraspinatus muscle, the implant delivery device comprising: a sheathdefining a lumen; and an implant disposed within the lumen of thesheath; transitioning the implant from an undeployed state within thesheath to a deployed state outside of the sheath; positioning theimplant over a partial thickness tear of a supraspinatus tendon of thepatient; attaching the implant to the supraspinatus tendon of thepatient while the implant is positioned over the partial thickness tearof the supraspinatus tendon of the patient.
 2. The method of claim 1,further comprising inserting the distal end of the implant deliverydevice into a subacromial bursa of the patient.
 3. The method of claim1, further comprising attaching the implant to the supraspinatus tendonusing staples.
 4. The method of claim 1, further comprising attachingthe implant to the supraspinatus tendon using an adhesive.
 5. The methodof claim 4, wherein the implant comprises a least one channel and aplurality apertures, and the method further comprising: injecting theadhesive into the at least one channel.
 6. The method of claim 5,wherein the adhesive elutes through the plurality of apertures afterbeing injected into the at least one channel.
 7. The method of claim 1,further comprising attaching the implant to the supraspinatus tendonsuch that at least a portion of the implant overlays the supraspinatustendon and at least a portion of the implant overlays a humerus bone. 8.The method of claim 1, wherein the implant comprises a bioabsorbablematerial.
 9. The method of claim 1, further comprising retracting thesheath to transition the implant from the undeployed state to thedeployed state.
 10. The method of claim 1, wherein the implantcomprises: a first layer having a sliding surface; and a second layeropposite the first layer and configured to engage the supraspinatustendon, the second layer comprising a biocompatible material and aplurality of pores for encouraging tissue growth.
 11. A method ofattaching an implant to a supraspinatus tendon of a patient comprising:inserting a sheet-like implant into a subacromial bursa of the patient;positioning the implant so that at least a portion of the implant coversa partial thickness tear of the supraspinatus tendon; and securing theimplant to the supraspinatus tendon while at least a portion of theimplant is covering the partial thickness tear of the supraspinatustendon.
 12. The method of claim 11, further comprising positioning theimplant so that at least a portion of the implant covers a humerus bone.13. The method of claim 11, further comprising: inserting the implantinto the subacromial bursa in a folded configuration; and unfolding theimplant while in the subacromial bursa.
 14. The method of claim 13,wherein the implant is inserted into the subacromial bursa within asheath of a delivery device.
 15. The method of claim 11, wherein theimplant comprises at least one channel in fluid communication with aplurality of apertures on a tendon-engaging surface of the implant. 16.The method of claim 11, wherein securing the implant to thesupraspinatus tendon comprises inserting one or more staples through theimplant and into the supraspinatus tendon.
 17. A method of treating arotator cuff of a shoulder of a patient comprising: inserting a distalend of an implant delivery device into a subacromial bursa within theshoulder of the patient, the implant delivery device comprising: asheath; and an implant disposed within the sheath in a foldedconfiguration; advancing the implant beyond the distal end of theimplant delivery device into the subacromial bursa; transitioning theimplant from the folded configuration to an unfolded configurationwithin the subacromial bursa; positioning the implant so that at least aportion of the implant covers a partial thickness tear of asupraspinatus tendon of the patient; and attaching the implant to thesupraspinatus tendon while at least a portion of the implant is coveringthe partial thickness tear of the supraspinatus tendon of the patient.18. The method of claim 17, where the implant is attached to thesupraspinatus tendon by inserting one or more staples through theimplant and into the supraspinatus tendon.
 19. The method of claim 17,further comprising positioning the implant so that at least a portion ofthe implant covers a humerus bone of the patient.
 20. The method ofclaim 17, where in the unfolded configuration the implant assumes aconcave shape.